Understanding the Influences of Microphysical Interactions with Pollution and Water on Dust Scattering Properties and Radiative Effects

Mineral dust is an integral component of the Earth system that influences weather and climate via a suite of complex interactions with the energy, water, and carbon cycles. Once aloft, dust can be carried by winds for intercontinental or even hemispherical transport. During long-range transport, the dust particles can become mixed with pollutants such as ammonium sulphate, ammonium nitrate, hydrochloric acid, and biomass burning particles, leading to changes of dust composition and hygroscopicity which in turn influence how dust interacts with water. In the past, many studies have investigated how pure, unpolluted dust aerosols interact with radiations, such as sunlight, infrared radiation and lidar signals. However, the scattering behaviors of polluted dust and hydrated dust are still poorly understood, which undermines our understanding of the role of dust in the climate system, as well as our capability to detect and retrieve dust aerosols using advanced remote sensing techniques. This project is to study how microphysical interactions with pollutants and water influence the scattering properties of dust aerosols and assess the implications for dust radiative effects and dust remote sensing. This goal is achieved through major tasks: First, the scattering properties of dust particles in different mixing states, including pure dust, coated dust and dust-aerosol coagulation, at different sizes and for different wavelengths will be computed using advanced scattering models; Second, the scattering properties of internally mixed dust particles will be compared with those of pure dust; Third, radiative transfer models will be used to simulate and compare the radiative effects of dust in different mixing states to understand the impacts of dust-pollution-water interactions on the climate system. The project involves mentoring two graduate students to be the next generation of atmospheric physicists. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.